Long travel soot blower with contoured rail



Nov. 9, 1965 R. E. CHAPPELL LONG TRAVEL SOOT BLOWER WITH CONTOURED RAIL2 Sheets-Sheet 1 Filed Oct. 22, 1962 INVENTOR. 302012 I (Zap v82],

Nov. 9, 1965 R. E. CHAPPELL LONG TRAVEL SOOT BLOWER WITH CONTOURED RAIL2 Sheets-Sheet 2 Filed Oct. 22, 1962 I rena 4 7 MW m Z a J 4 N m #8 My,f a .m M 4m m .M a 7 p M h 7 6 a a W 0 0 0 0 0 v H 0 fimfimwhxxQ BY /Mo*!m.

United States Patent 3,216,044 LONG TRAVEL SOOT BLOWER WITH CONTOUREDRAIL Robert E. Chappell, Lancaster, Ohio, assignor to Diamond PowerSpecialty Corporation, Lancaster, Ohio, a corporation of Ohio Filed Oct.22, 1962, Ser. No. 232,010 4 Claims. (Cl. -317) The present inventionbroadly pertains to apparatus for cleaning the heat exchanger surfacesof heat exchanger apparatus such as high capacity power boilers and thelike, and more particularly to a cleaning apparatus employing a cleaningtube provided with at least one nozzle in the forward end thereof whichis movable to and from a retracted position and a projected positionwithin the interior of a heat exchanger apparatus during which apressurized blowing medium is discharged against the heat exchangersurfaces to be cleaned. More specifically, the present invention relatesto an improved cleaning apparatus incorporating compensating meanstherein for compensating for the gravitational deflection of thecleaning tube during the projecting and retracting travel thereofmaintaining a substantially linear path of travel of the forward nozzleend thereof assuring uniform cleaning of the heat exchanger surfacestraversed thereby.

Cleaning apparatuses of the general type to which the present inventionis applicable are in widespread use in industry for effecting a removalof soot, slag, and other extraneous deposits from the surfaces of heatexchanger apparatuses of various types. Cleaning apparatuses, or sootblowers as they are conventionally referred to, of the so-calledlong-retracting or long-travel type, incorporate a cleaning or lancetube which is adapted to be disposed exteriorly of and in alignment witha wall port in the wall of a heat exchanger apparatus and is movablefrom a retracted position wherein the forward or nozzle end thereof isdisposed contiguous with the wall port to a projected position withinthe interior of the heat exchanger apparatus. Conventionally, the lancetube is rotated during its longitudinal movement and a pressurizedblowing medium such as steam or air, for example, is discharged in ahelical blowing pattern from one or a plurality of nozzles disposedalong the forward end portion of the lance tube. The impingement of thepressurized blowing medium against the heat exchanger surfaces effects aremoval of the soot, slag and other extraneous deposits therefrommaintaining a high thermal efiiciency of the heat exchanger apparatus.

The increase in the size and the capacity of modern high pressure powerboilers has necessitated an increase in the length of long travel typesoot blowers in order to order to achieve adequate cleaning coverage ofthe tube banks including the pendant type super heater and reheaterbundles disposed within the interior of the boiler. The relativedisposition of such tube bundles necessitates that the path of travel ofthe nozzles from which the blowing medium is discharged be carefullycontrolled so as to provide substantially uniform cleaning coverage ofthe heat exchanger surfaces and to avoid any mechanical interferencebetween the lance tube and heat exchanger surfaces and attendantsupporting structure.

The increasing length of the lance tube employed in long retracting typesoot blowers has caused an increasing problem as a result of thegravitational deflection of the lance tube which results in an arcuatepath of travel of the nozzle end portion of the lance tube creatinginterference and nonuniform cleaning in some instances. This verticaldeflection of the nozzle end of the lance tube becomes progressivelygreater as the lance tube approaches the fully projected position. Theresultant progressive vertical deflection of the nozzle end portion ofthe lance tube with respect to a true linear path of travel causes adeviation in the distance of the nozzles from the heat exchangersurfaces to be cleaned resulting in a nonuniform cleaning pattern. Afurther problem is created when relatively closely stacked tube bundlesare being cleaned whereby the close approach of the cleaning nozzlestoward the heat exchanger surfaces presents the hazard of erosin of thetube bundles exposed to a close direct discharge of the blowing medium.In an attempt to overcome this lance tube deflection problem, variousstructural design modifications of the lance tube have been employed orproposed for use. These changes however, have been unsuccessful ineliminating lance tube deflection and have resulted in an increase inthe weight, complexity and cost in long travel type soot blowers.

It is accordingly, a primary object of the present invention to providean improved soot blower of the long retracting type which overcomes theproblems associated with lance tube deflection that have beenencountered in soot blowers of similar type heretofore known.

Another object of the present invention is to provide an improved longretracting type soot blower employing guide means therein which effectsa controlled vertical displacement of the lance tube in an amount so asto compensate for the vertical displacement of the nozzle end portion ofthe lance tube as occasioned by lance tube deflection providing for asubstantially linear path of travel of the nozzles relative to the heatexchanger surfaces being cleaned.

Still another object of the present invention is to provide an improvedsoot blower of the long retracting type which is of simple design,durable operation, of economical manufacture and which embodiescompensating means therein which are readily adaptable for compensatingfor the vertical deflection of the nozzle end of the lance tubeconsistent with such factors as the length of the lance tube, thespecific direction of travel thereof, and the clearance and interferencecharacteristics of the heat exchanger surfaces to be cleaned.

Other objects and advantages of the present invention will becomeapparent from the following detailed description taken in conjunctionwith the accompanying drawings, wherein:

FIGURE 1 is a longitudinal side elevation view of a soot blowerconstructed in accordance with the preferred embodiments of the presentinvention and illustrated in two sections which are connected to eachother along the lines indicated at AA;

FIG. 2 is a fragmentary perspective view of the forward end portion ofthe soot blower shown in FIGURE 1;

FIG. 3 is a fragmentary end elevation view partly in section of theforward end of a lance tube employed in the soot blower shown in FIGURE1;

FIG. 4 is an alternate satisfactory form of a nozzle arrangement in theforward end portion of a lance tube;

FIG. 5 is a graphical illustration of the vertical deflection of atypical lance tube as a function of its longitudinal projectingposition, and

FIG. 6 is a typical substantially linear path of travel of the nozzleend of a lance tube of a long retracting type soot blower incorporatingcompensating means in accordance with the present invention.

Referring now in detail to the drawings and as may be best seen inFIGURES 1-2, a long retracting or long travel type soot blower to whichthe present invention is applicable, comprises guide means such as arail 10 which is adapted to be positioned exteriorly of a wall 12 of aheat exchanger apparatus provided with an opening or wall port 14therethrough. A carriage 16 is movably supported on a track plate 18aflixed to the underside of the lower flange of the rail 10 such as byrollers 20 disposed in rolling bearing contact against the upperprojecting surface of the track plate. The carrier 16 is movable alongthe rail from a fully retracted position as shown in FIGURE 1 to a fullyprojected position in which the carriage is positioned at the forwardend portion of the rail 10 adjacent to the wall 12 of the heat exchangerapparatus.

A lance tube 22 is rotatably supported at the rearward end thereof bythe carriage 16 and extends therefrom in a direction in alignment withthe wall port 14. The forward end portion of the lance tube 22 isrotatably and rnovably supported by suitable supporting means such as aroller support 24 connected to the forward end of the rail 10 and isdisposed adjacent to the wall port 14. When lance tubes such as thelance tube 22 of a substantially long length are employed, a sag ordeflection of the lance tube will occur between the forward rollersupport 24 and the carriage 16. In such cases, it is usually desirableto employ an intermediate support such as the intermediate rollersupport 26 as shown in FIGURE 1, which supports the mid-portion of thelance tube while in the fully retracted position as well as during itsprojecting and retracting travel.

The forward roller support 24 as best seen in FIGURE 2, comprises ayoke-shaped member 28 aflixed to and depending from the forward end ofthe rail 10. A roller bracket 30 is pivotally secured by means of a pin32 to the lower portion of each of the legs of the yokeshaped member 28.A roller 34 is rotatably mounted in each of the roller brackets 30 andis adapted to rotatably and slidably contact the peripheral surface ofthe lance tube 22. A bracket 36 is connected to the lower end of theyoke-shaped member 28 and is provided with a pair of adjusting screws 38which extend upwardly and are disposed with the ends of the shankportions thereof in abutting relationship against the undersides of theroller brackets 30 providing for appropriate vertical adjustment of thelance tube relative to the wall port 14.

The intermediate roller support 26 which is usually employed when lancetubes of about 25 feet or greater in length are used, comprises atrolley bracket 40 which is disposed in rolling engagement on the trackplate 18 of the rail 10, and is movable therealong from a positionsubstantially in the middle of the rail when the carriage is in thefully retracted position to a position adjacent to the wall port 14along the forward end portion of the rail when the carriage and thelance tube are in the fully projected position. The intermediate rollersupport 26 is movable from the mid-position to the forward position inresponse to the projecting travel of the carriage and is retracted tothe mid-position by suitable latching means on the carriage which aredisengaged when the intermedi ate roller support attains themid-position during the retracted travel of the carriage. The lowerportion of the intermediate roller support 26 is provided with suitablesliding or rolling supports on which the peripheral surface of the lancetube is rotatably and rnovably disposed.

The forward end of the lance tube 22 is slidably disposed within thewall port 14 which conventionally incorporates suitable sealing means(not shown) for preventing the escape of the hot combustion gases fromwithin the interior of the heat exchanger apparatus through the wallport. The forward end of the lance tube as best seen in FIGURES 3 and 4,is provided with one or more nozzles through which a pressurized blowingmedium such as air or steam, for example, is discharged during thetraversing movement of the lance tube during a cleaning operation. Inthe particular arrangement shown in FIGURE 3, a pair of diametricallydisposed nozzles 42 are provided in the nozzle end of the lance tube 22which discharge the blowing medium in a direction substantiallyperpendicular to the longitudinal axis of the lance tube.

An alternate satisfactory arrangement is illustrated in FIGURE 4 whereina nozzle 44 is provided for discharging the blowing medium in adirection substantially perpendicular to the axis of the lance tube 22and an angularly disposed nozzle 46 is incorporated for discharging theblowing medium in a direction forwardly of and angularly inclinedrelative to the longitudinal axis of the lance tube. The use of one ormore angularly inclined nozzles in accordance with the embodiment shownin FIGURE 4 provides advantages in some installations particularly whenthe angle of deflection of the nozzle end of the lance tube becomesrelatively large. In either event, the particular type of nozzlearrangement employed is selected in consideration of the nature andconfiguration of the heat exchanger surfaces to be cleaned so as toprovide substantially uniform coverage and optimum cleaning action.

When the lance tube 22 is in the fully retracted position, the nozzleend thereof is disposed in the wall port 14 whereby the nozzle end ofthe lance tube is protected from the hot combustion gases within theinterior of the heat exchanger apparatus. At the initiation of theoperation of the soot blower, the lance tube commences to rotate and isadvanced from the fully retracted position outwardly toward theprojected position. The discharge of the blowing medium from the nozzlein the forward end of the lance tube is delayed until the lance tube hastravelled to a position slightly beyond the water wall tubes 48positioned along the inner surface of the heat exchanger apparatus.Similarly, the discharge of the blowing medium from the nozzle is haltedprior to the completion of the retracting movement of the lance tubewhen the nozzles approach a position spaced from the water wall tubes 48to avoid direct close range impingement of the blowing mediumthereagainst which may result in the erosion thereof.

The supply of a pressurized blowing medium to the interior of the lancetube 22 is conveniently achieved by a feed tube 50 that is stationarilyconnected at its rearward end to a supply valve 52 mounted at theoutward end of the rail 10. The supply valve 52 is connected to asuitable supply conduit 54 which is disposed in communication with amain supply header (not shown) to which each of the other soot blowersmounted on the heat exchanger apparatus may suitably be connected.

The supply valve 52 can be operated mechanically such as by linkage 55responsible to the coaction with the carriage 16 during its longitudinalmovement along the rail 10 and is conventionally moved to an openposition when the carriage has advanced to a position wherein the nozzleend of the lance tube is disposed beyond the water wall tubes 48 alongthe inner surface of the heat exchanger apparatus. Alternatively, thesupply valve 52 can be actuated by a suitable solenoid operativeresponsive to the tripping of suitable limit switches by the carriage inresponse to its movement between the fully projected position andretracted position.

The feed tube 50 extends forwardly from the supply valve 52 and isdisposed in telescopic relationship within the interior of the lancetube 22. The feed tube extends for substantially the entire length ofthe rail 10 to assure constant communication with the interior of thelance tube as the carriage is advanced to the fully projected position.Suitable sealing means (not shown) are incorporated in the carriage 16providing a pressure-tight connection between the periphery of the feedtube and the inner surface of the lance tube to prevent the escape ofany pressurized blowing medium therebetween.

Since the feed tube is substantially the same length as the lance tube,there is a tendency for the feed tube to sag when the carriage and lancetube are in the fully projected position. When the length of the feedtube is relatively great, it is usually preferred to provide a feed tubesupport roller 56 as shown in FIGURE 1 which is movably mounted on therail 10 in a manner similar to the intermediate roller support 26 and ismovable by the carriage 16 to a position substantially at the midpointof the rail 10. Suitable stop means are provided on the feed tubesupport roller 56 and the rail to prevent further movement of the feedtube support roller beyond the midpoint of the rail during the continuedadvancing movement of the carriage. The feed tube support roller 56 isreturned to the fully retracted position as shown in FIGURE 1 by thecoaction with the carriage during the latter half of its retractingmovement. By virtue of this arrangement, the sag of the feed tube isminimized when the carriage is on the fully projected position byproviding support at substantially the mid-point thereof preventing anybinding or skewing of the feed tube during its telescopic slidingmovement into and out of the lance tube.

The movement of the carriage 16 and lance tube as well as thesimultaneous rotation of the lance tube during its projecting andretracting travel is achieved in accordance with the exemplaryconstruction shown in the drawings by a reversible motor 58 drivinglyconnected to a gear box 69 mounted adjacent to the forward end of therail 10 as may be best seen in FIGURE 2. The reversible motor 58 mayeither be of a fluid actuable type such as an air or hydraulic motor or,alternatively, may comprise a reversible electric motor. The outputshaft of the gear box 60 is drivingly coupled to a suitable elon gateddrive shaft 62 of an irregular cros section such as a square crosssection, for example, which extends substantially for the entire lengthof the rail 10 and is slidingly and rotatably coupled to a driven memberon the carriage having a correspondingly contoured bore therethrough forslidably engaging the drive shaft. The driven member on the carriage maysuitably be coupled to suitable gears for effecting rotation of thelance tube and for translation of the carriage along the rail 10.

In the exemplary embodiment shown in the drawings, the translation ofthe carriage between the projected and retracted positions is achievedby a rack 64 afi ixed to and extending centrally of the under side ofthe rail 10 with which a pinion 66 is disposed in constant meshingrelationship and which is drivingly connected to the drive shaft 62 bythe driven member on the carriage. In accordance with this arrangement,the rotation of the reversible motor 58 in one direction eifectsmovement of the carriage and translation and rotation of the lance tubein one direction and upon reversal of the direction of rotation of thereversible motor, the direction of rotation and translation of the lancetube is likewise reversed.

Energization of the reversible motor can be achieved manually orremotely by the operator or alternatively, can be achieved in accordancewith a preselected sequentially phased operating cycle as controlled byan automatic control system. On energization of the reversible motor,the carriage commences to advance toward the projected position until ittrip a suitable sensing device such as a limit switch LS1 mounted on therail 10 as shown in FIGURE 1. The tripping of the forward control limitswitch LS1 signals the control circuit of the soot blower which reversesthe direction of rotation of the reversible motor whereby the carriagecommences its retracting movement. When the fully re tracted position isattained, the carriage actuates a suitable sensing device such as a reartravel limit switch LS2 which signals the control circuit andde-energizes the reversible motor. The carriage and lance tube remain inthe fully retracted position preparatory to the next cleaning cycle.

Alternate satisfactory power means for effecting movernent of thecarriage and lance tube along the rail can be achieved by installing asuitable electric or fluid actuated reversible motor directly on thecarriage 16 which is drivingly connected to the pinion 66 and thegearing for rotating the lance tube. Alternatively, the reversible motor58 and gear box 60 as shown in FIG- URES 1 and 2, can be mounted at therearward end of the rail 10 adjacent to the supply valve providing the 6same driving action as hereinbefore described. The motor means as wellas the entire rail of the soot blower is preferably protected by asuitable canopy or shroud 68 to protect the several components of thesoot blower from the elements and any dust or dirt particles which mightinterfere with the proper function thereof.

It will be apparent from the description of the soot blower ashereinabove set forth that, as the lance tube 22 is moved from the fullyretracted position as shown in FIGURE 1 toward the projected position,the nozzle end portion of the lance tube will progressively benddownwardly in a vertical direction in response to the gravitationalbending or deflection of the overhanging portion of the lance tubebetween the nozzle end and the front roller support 24 disposed adjacentto the wall port 14. A typical graphical illustration of the verticaldeflection of the nozzle end portion of a lance tube is illustrated inFIGURE 5 as a function of the projecting position of the lance tube fromthe front roller support. As shown in FIGURE 5, the vertical deflectionexpressed in inches of the nozzle end portion of a non-compensated lancetube having a length of 45 feet attains a magnitude of almost 3 feet atthe point of maximum projection. This necessitates a relatively largecavity in the tube bundles to provide satisfactory clearance for thelance tube in addition to causing a non-uniform cleaning pattern.

The specific deflection obtained on a lance tube will vary, depending onthe specific physical characteristics of the material of which it iscomprised as well as the weight, diameter, and wall constructionthereof. This deflection occurs whether the lance tube travels in a substantially horizontal plane or is angularly inclined from the horizontalin accordance with a specific layout of the tube bundles and heatexchanger surfaces. In either event, it will be apparent that adeviation in the position of the nozzles in the nozzle end of the lancetube occurs between the initial portion of its outward travel and at thefully projected position which, if not compensated for, results in anunevenness in the cleaning action as well as in some instances producingmechanical interference and erosion of the tubes being cleaned.

In accordance with the practice of the present invention, the verticaldeflection of the lance tube is compensated for so as to provide asubstantially linear path of travel of the nozzle end portion thereofbetween the fully retracted and the fully projected positions. In thespecific emboliment shown, the compensation is achieved by providing anappropriate contour in at least a portion of the rail 10 whereby thecarriage and the rearward end of the lance tube 22 is verticallydisplaced in response to the longitudinal travel of the carriagetherealong providing a corresponding corrective vertical displacement ofthe nozzle end portion of the lance tube. A graphical illustration of acompensated path of travel of the nozzle end portion of the lance isillustrated in FIGURE 6 wherein it is noted that the deviation of thepath of travel of the nozzle end from a true linear path is relativelylow throughout the entire travel of the lance tube.

The particular path of travel of the nozzle end of the lance tube asshown in FIGURE 6 was obtained on the same soot blower employed fortabulating the curve shown in FIGURE 5. The soot blower was not providedwith an intermediate roller support such as the support 26 as shown inFIGURE 1 whereby a sagging of the lance tube in the fully retractedposition occurred. As a result of this sag, the initial outward movementof the lance tube produced an upward movement of the nozzle end abovethe horizontal zero reference line. As the nozzle subsequentlyapproached the zero line, the compensating means hereinafter describedeflect correction of the downward nozzle deflection maintaining asubstantially linear path in comparison to the arcuate path of thenon-compensated lance tube shown in FIGURE 5.

The corrective deflection of the nozzle end portion of the lance tube isachieved, as may be best seen in FIG- URE 1, by providing an arcuatelyvertically depressed contour along at least a portion of the rail whichdeviates from a reference line indicated generally at 70 by a magnitudeselected relative to the longitudinal spacing thereof from the frontroller support 24 to provide an angular deviation of the outer endportion of the lance tube relative to the reference line that willeffect a vertical lifting of the nozzle end portion of the lance tube inan amount sufficient to place it in a position substantially coincidingwith a linear path of travel.

in accordance with this relationship, the rearward end portion of therail 10 along the section generally designated as W is of asubstantially straight configuration corresponding substantially to theplane of the reference line 70. The length of the section W is dictatedby the length of the overhanging portion of the lance tube beyond thewall port 14 which will produce only a negligible deflection from thelinear path of travelobviating the need of any compensation. The rail 10then commences a downward arcuate contour as provided by the sectiongenerally indicated at X until a point generally indicated at Y ofmaximum deviation of the rail from the reference line 70 is attained.During the movement of the carriage along the rail section X to thepoint Y, the rearward end of the lance tube is vertically moveddownwardly effecting a corresponding upward vertical movement of thelance tube about the fulcrum provided by the forward roller support 24compensating for the progressive increase in the deflection of thenozzle end portion of the lance tube relative to the front support.

Movement of the carriage toward the fully projected position beyond thepoint Y is achieved along a track section generally indicated at Z whichis arcuately inclined upwardly and progressively approaches thereference line 70. The decrease in the vertical deflection of the railsection Z relative to the reference line 70 is necessitated by thedecrease in the length of the leverage arm between the front rollersupport 24 and the carriage 16 which provides for a magnification of thevertical correction of the nozzle end portion of the lance tube as thecarriage approaches the fully projected position. Accordingly, theangularity of the portion of the lance tube disposed exteriorly of thewall of the heat exchanger apparatus decreases as the carriage movesalong the rail section Z toward the projected position whereby thenozzle end portion of the lance tube is maintained in a substantiallylinear path of travel. A corresponding correction of the deflection ofthe nozzle end portion of the lance tube is achieved during theretracting movement of the lance tube providing therewith asubstantially linear path of the retracting travel of the nozzle endthereof. The corrective action supplied by the arcuate contour of therail sections W, X and Z, is illustrated in FIGURE 6 and corresponds tothat achieved by the contoured rail having a configuration as shown inFIGURE 1.

A rail contoured in accordance with the configuration as shown in FIGURE1 is effective to provide a substantially linear path of travel of thenozzle end portion of the lance tube in accordance with the graph asportrayed in FIGURE 6. As shown in this figure, the maximum deviation ofthe nozzle end portion of the lance tube from a true linear paththroughout its travel is less than 7 inches in comparison to a maximumdeflection of almost 3 feet of a non-compensated lance tube as portrayedin FIGURE 5. A further improvement in the linearity of the path oftravel of the nozzle end of the lance tube can be provided byincorporating an intermediate roller support such as the roller support26 shown in FIGURE 1 whereby the sag of the lance tube when the carriageis in the fully retracted position is substantially eliminated. Theelimination of this sag is effective to eliminate the upward deviationof the nozzle end portion of the lance tube from the true linear path asshown in FIGURE 6 during the first 25 feet of travel providing for asubstantially linear path throughout the entire projecting andretracting travel thereof. Tests conducted on the soot blower employingsuch an intermediate roller support reduced deviations of the nozzle endof the lance tube to less than 3 inches above and below the theoreticalreference line.

Further improvements and compensation of the deflection of the nozzleend portion of the lance tube can be achieved by varying the height ofthe front roller support 24 and the wall port 14 relative to the linearreference line effecting a change in the fulcrum about which the lancetube bends providing additional correction in combination with thatprovided by the contoured rail. It will be further noted that thecontoured portion of the rail is comprised of a series of straightsections rigidly aflixed in end-abutting relationship to provide thedesired contour. By employing a rail 10 which is formed in a smootharcuate curvature along the contoured section thereof,,m0re accuratecontrol of the path of travel of the lance tube can be achieved. It willalso be understood that by further modifying the particular contour ofthe rail 10 consistent with a particular type of lance tube, a path oftravel of the nozzle end portion thereof can be achieved which is in atrue linear direction coinciding with the horizontal zero reference lineas shown in FIGURE 6. For practical purposes, however, lance tubedeflections of a magnitude as illustrated in FIG- URE 6 are suitable formost installations and are sufiicient to achieve satisfactory uniformcleaning of the heat exchanger surfaces traversed thereby.

While it will be apparent that the preferred embodiments of theinvention disclosed are well calculated to fulfill the objects abovestated, it will be appreciated that the invention is susceptible tomodification, variation and change without departing from the properscope or fair meaning of the subjoined claims.

What is claimed is:

1. A long travel soot blower comprising an elongated rail, a carriagemovably mounted on said rail, a lance tube having the rearward endthereof movably supported on said carriage and extending therefrom in adirection in alignment with a wall port in the wall of a heat exchangerapparatus, said lance tube formed at its forward end with at least onenozzle for discharging a pressurized blowing medium against the heatexchanger surfaces to be cleaned, means for rotating said lance tube andfor moving said carriage and said lance tube to and from a retractedposition and a projected position, sup port means disposed adjacent tothe Wall port for movably supporting said lance tube while in saidprojected and retracted positions and during its movement therebetween,at least a portion of said rail formed with a contour verticallydisplaced from a reference plane extending between the ends of said railfor vertically moving said carriage and said rearward end of said lancetube relative to said support means in response to movement of saidcarriage along said rail compensating for the gravitational deflectionof said lance tube and providing for a substantially linear path oftravel of the nozzle end of said lance tube between said positions.

2. A long travel soot blower comprising an elongated rail adapted to bedisposed exteriorly of a heat exchanger apparatus, a carriage movablymounted on said rail, a lance tube having the rearward end thereofmovably supported on said carriage and extending therefrom in adirection in alignment with a wall port in a wall of a heat exchangerapparatus, said lance tube formed at its forward end with at least onenozzle for discharging a pressurized blowing medium against the heatexchanger surfaces to be cleaned, power means for rotating said lancetube and for moving said carriage and said lance tube to and from aretracted position wherein the nozzle end of said lance tube is disposedcontiguous to the wall port and a projected position wherein said nozzleend is disposed within the interior of the heat exchanger apparatus,support means disposed adjacent to the wall port for movably supportingsaid lance tube, at least a portion of said rail formed with a contourvertically displaced from a reference plane extending between the endsof said rail for vertically moving said carriage and said rearward endof said lance tube relative to said support means in response to thelongitudinal travel of said carriage along said rail and compensatingfor the gravitational deflection of said lance tube providing for asubstantially linear path of travel of said nozzle end between saidprojected and said retracted positions.

3. A long travel soot blower comprising an elongated rail adapted to bedisposed in a substantially horizontal stationary position exteriorly ofa heat exchanger apparatus, a carriage movably mounted on said rail, alance tube having the rearward end thereof movably supported on saidcarriage and extending therefrom in a direction in alignment with a wallport in a wall of a heat exchanger apparatus, said lance tube formed atits forward end with at least one nozzle for discharging a pressurizedblowing medium against the heat exchanger surfaces to be cleaned, powermeans for rotating said lance tube and for moving said carriage and saidlance tube in a substantially horizontal direction along said rail toand from a retracted position and a projected position, support meansfor movably supporting said lance tube at a position adjacent to thewall port, at least a portion of said rail formed with a longitudinallyextending contour vertically displaced from a horizontal reference planeextending between the ends of said rail for vertically moving saidrearward end of said lance tube relative to said support means inresponse to the longitudinal travel of said carriage along said rail andcompensating for the gravitational deflection of said lance tube duringthe projecting and retracting travel thereof and providing for asubstantially linear path of travel of the nozzle end thereof betweensaid projected and said retracted positions.

4. A long travel soot blower comprising a rail adapted to be disposedexteriorly of a heat exchanger apparatus, a carriage movably mounted onsaid rail, a lance tube having the rearward end thereof movable androtatably supported on said carriage and extending therefrom in adirection in alignment with a wall port in a wall of a heat exchangerapparatus, said lance tube formed at its forward end with at least onenozzle for discharging a pressurized blowing medium against the heatexchanger surfaces to be cleaned, power means for rotating said lancetube and for moving said carriage and said lance tube to and from aretracted position and a projected position, supporting means formovably supporting said lance tube at a position adjacent to the wallbox, at least a portion of said rail formed with a vertically disposedarcuate contour for vertically moving said rearward end of said lancetube relative to said supporting means responsive to the longitudinaltravel of said carriage compensating for the gravitational deflection ofsaid lance tube and providing for a substantially linear path of travelof the nozzle end of said lance tube between said retracted and saidprojected positions.

References Cited by the Examiner UNITED STATES PATENTS 1,599,283 9/26Phillips 122-390 X 2,897,532 8/59 Cantieri 153 17 3,160,907 12/64 Tollow15-317 FOREIGN PATENTS 439,291 12/35 Great Britain.

0 ROBERT W. MICHELL, Primarv Examiner.

F. L. MATTESON, WALTER A. SCHEEL Examiners.

1. A LONG TRAVEL SOOT BLOWER COMPRISING AN ELONGATED RAIL, A CARRIAGEMOVABLY MOUNTED ON SAID RAIL, A LANCE TUBE HAVING THE REARWARD ENDTHEREOF MOVABLY SUPPORTED ON SAID CARRIAGE AND EXTENDING THEREFROM IN ADIRECTION IN ALIGNMENT WITH A WALL PORT IN THE WALL OF A HEAT EXCHANGERAPPARATUS, SAID LANCE TUBE FORMED AT ITS FORWARD END WITH AT LEAST ONENOZZLE FOR DISCHARGING A PRESSURIZED BLOWING MEDIUM AGAINST THE HEATEXCHANGER SURFACES TO BE CLEANED, MEANS FOR ROTATING SAID LANCE TUBE ANDFOR MOVING SAID CARRIAGE AND SAID LANCE TUBE TO AND FROM A RETRACTEDPOSITION AND A PROJECTED POSITION, SUPPORT MEANS DISPOSED ADJACENT TOTHE WALL PORT FOR MOVABLY SUPPORTING SAID LANCE TUBE WHILE IN SAIDPROJECTED AND RETRACTED POSITIONS AND DURING ITS MOVEMENT THEREBETWEEN,AT LEAST A PORTION OF SAID RAIL FORMED WITH A CONTOUR VERTICALLYDISPLACED FROM A REFERENCE PLANE EXTENDING BETWEEN THE ENDS OF SAID RAILFOR VERTICALLY MOVING SAID CARRIAGE AND SAID REARWARD END OF SAID LANCETUBE RELATIVE TO SAID SUPPORT MEANS IN RESPONSE TO MOVE MENT OF SAIDCARRIAGE ALONG SAID RAIL COMPENSATING FOR THE GRAVITATIONAL DEFLECTIONOF SAID LANCE TUBE AND PROVIDING FOR A SUBSTANTIALLY LINEAR PATH OFTRAVEL OF THE NOZZLE END OF SAID LANCE TUBE BETWEEN SAID POSITIONS.